High power LEDs used for illumination generate much heat that needs to be sinked to an external heat sink. Typically, a packaged LED, such as shown in prior art FIG. 1, includes an LED die 10, a ceramic submount 12 with electrodes bonded to the LED die electrodes, a metal heat conductor slug 14, a reflective cavity 16, solderable surface mount leads 18 connected to the submount electrodes for soldering to a printed circuit board (PCB), a molded plastic body 20, and a lens 22 glued to the body.
The PCB (not shown) may have a metal body with an electrically insulating surface over which metal traces are formed. The metal traces may interconnect multiple LED packages, and the metal leads typically terminate in connectors at the edge of the PCB for attachment to power supply leads. The metal slug 14 conducts heat from the LED to the PCB body, which is then air cooled.
It is conventional to solder the package leads to a circuit board to firmly secure the package to the heat sinking PCB. Providing the package with solderable leads also allows the LED package to be treated as an integrated circuit package, so conventional IC mounting and soldering techniques can be used when mounting LED packages onto PCBs. Essentially, the high power LED package evolved from the high power IC package design.
As a consequence of the solderable connections, the equipment manufacturers that purchase and mount high power LED packages must invest in soldering technologies, such as solder bath systems or equipment that solders the connections individually. Different manufacturers have different competencies for soldering LED packages to PCBs, making it difficult for some manufacturers to handle high power LED packages.
Further, accurately positioning the package on the PCB is difficult in that the package may be slightly out of position over the PCB pads yet still be adequately soldered onto the PCB pads. Thus, the light source will not be precisely located with respect to the PCB.
What is needed is a package for high power, high heat generating LEDs that simplifies the electrical connection to a power supply and provides excellent heat sinking of the LED without the use of solder.